Factors affecting water chemistry of alpine lakes

During a four-year study (1988–1991), 413 lakes in the Central Alps (Italy, Switzerland and Austria) were investigated to quantify their acidification. The ionic content of the lakes was generally low: 68% of them had alkalinity values of less than 200 µeq 1^–1 and were regarded as sensitive to acidification. Moreover, 36% of the lakes showed alkalinity values of less than 50 µeq 1^–1. Redundancy Analysis was used to relate the hydrochemistry of 187 lakes to their catchment characteristics. Calcite weathering was the main factor influencing lake chemistry. The same analysis, applied to a subset of 101 lakes lying in watersheds exclusively composed of silicic rocks, showed that lake chemistry was influenced by silicate weathering and nitrogen uptake. These processes were found to be mainly related to lake altitude and the fraction of the watershed not covered by vegetation, i.e. controlled by temperature. The importance of these relations to explain the pH shift produced by climatic variation is also discussed.     

Periphyton and sphagnicolous protists of dystrophic bog lakes (Brandenburg, Germany): II. Characteristic species and trophy of the lakes

Glass-slides were exposed in four different bog lakes located in great forest areas in Northern Germany, about 100 km north of Berlin, in order to examine the protist community of these dystrophic, acid lakes. Species composition and succession of the periphyton were studied during one year. The four investigated bog lakes exhibit similar species compositions, most of the species were present in each of the four lakes. The periphyton was composed of a great variety of protist species. Specimens of all major flagellated protists and of most of the ciliate taxa were found on the slides. Many of these species are ubiquitous. Some species, however, like the flagellates Spongomonas sacculus, Rhipidodendron huxleyi, Cyathobodo sp., and Pseudodendromonas vlkii as well as the ciliates Ophrydium hyalinum, Leptopharynx costatus, Uroleptus caudatus, and Platyophrya sphagni are found more frequently in acid waters. A regular and common occurrence of these species partly characterizes the acid Sphagnum bogs. Besides that, common species like Bodo spp., Cryptomonas spp., Goniomonas truncata, Chilodonella uncinata, Vorticella sp., and Cyrtolophosis mucicola are represented in the periphyton. Examinations of the testate amoebae in the Sphagnum mats show a very different species composition compared to earlier studies.

The investigated bog lakes revealed mesotrophic conditions. In the upper regions of the Sphagnum mats and in the center of the larger bog lakes, oligotrophic conditions still prevail. The lower regions of the Sphagnum mat and the smaller lakes, however, are influenced by the partly degradation of plants and the run-off water from surrounding land. In comparison to earlier studies, the species composition indicates a beginning eutrophication of the bog lakes. A direct anthropogenic impact can be excluded.     

Periphyton and sphagnicolous protists of dystrophic bog lakes (Brandenburg, Germany): I. Annual cycles, distribution and comparison to other lakes

The periphyton of acid, dystrophic bogs was investigated. Glass-slides were exposed in four different bog lakes about 100 km north of Berlin, Germany, in order to examine the species composition and the annual cycle of the protist community. The annual cycles of the periphyton in bog lakes were comparable to those in other mesotrophic lakes: During the winter months small heterotrophic flagellates (HF) dominated the periphyton community. Besides that bacterivorous ciliates were present as typical pioneer species. At the end of the ice covering, almost exclusively unicellular green algae colonized the slides. In May high abundances of ciliates and choanoflagellates were observed. At the same time, a maximum of species was reached. From August to October peritrich ciliates significantly contributed to the periphyton. Their number decreased when early frosts occurred.

The four investigated bog lakes exhibit very similar species compositions, almost all of the species were present in each of the four lakes. Differences were only distinct concerning the dominance of some protistan groups. The largest deflections, however, occurred not between two lakes, but between two habitats within one lake: The upper 30 cm of the Sphagnum mat comprise two very different protistan communities, determined by a strong vertical zoning. Due to the different light and nutrient conditions, the slides of the upper region exhibited a denser colonization, mainly consisting of autotrophic cryptomonads and vagile ciliates. In contrast to this, the slides of the deeper region were mainly colonized by heterotrophic flagellates and sessile peritrich ciliates.     

云贵高原湖泊夏季浮游植物组成及多样性

浮游植物是水生生态系统中重要的初级生产者,对维持水生态系统的平衡起着十分重要的作用.根据2008年云贵高原湖泊丰水期浮游植物调查数据,系统地分析了云贵高原13个湖泊中浮游植物的种群密度、生物量、组成及其多样性.云贵高原13个湖泊中共鉴定出浮游植物7门109种(绿藻52种、蓝藻23种、硅藻20种、其他14种).13个湖泊浮游植物Shannon-Wiener指数在0.5-2.2之间,其值大小与单个环境因子无显著相关.相关分析发现浮游植物总量与总氮、总磷、CODMn、硝态氮含量显著正相关,物种丰富度与总氮、总磷(0.1mg/L范围内)、CODMn含量亦显著正相关.另外,研究也发现各湖泊间浮游植物组成的相似性与各湖泊间营养状态差异显著负相关.由此可见,湖泊的营养状态不仅影响浮游植物的总量、组成以及物种丰富度,而且也影响各湖泊物种组成的相似性.     

Factors promoting persistence of the bloom-forming Gonyostomum semen in temperate lakes

The nuisance large flagellate Gonyostomum semen (Raphidophyceae) is typical for brown-water lakes in temperate and boreal regions. This study is focused on two annual cycles of G. semen in shallow temperate lakes (one of which stratifies) with a particular emphasis on the species’ ecology and its potential impact on the alternation of phytoplankton assemblages. Temperature and phosphorus were the main forces driving seasonal growth of the raphidophyte. G. semen occurred at a broad temperature range and prevailed for the extended period from spring to late autumn at maximum biovolume and forming up to 98.7% of total phytoplankton in June–July and/or September. The species exclusively dominated under phosphate-replete conditions and caused heavy blooms in the stratified lake. The species outcompeted other flagellates in the lakes; considerable fluctuations in phytoplankton species composition occurred during the periods at low G. semen biovolume.     

Assessment of river habitat in Brandenburg, Germany

A habitat assessment of 1,707 km of rivers in the Federal State of Brandenburg, Germany, was undertaken using the desk-based ‘overview method’. This method includes the analysis of different sources such as topographic and thematic maps, reports, remote sensing data, and interviews with authorities. It compares actual habitat conditions with natural conditions, and assesses the human disturbances using a seven-step scale. Results show, that in Brandenburg more than 50% of surveyed river units are heavily (class 5) to totally disturbed (class 7) and only slightly more than 20% are undisturbed (class 1) to little disturbed (class 2). Main human disturbances are canalization, bank stabilizations, flood control, migration barriers, and agricultural and urban development in the floodplain. All survey data and maps are embedded in a geographical information system (GIS) that not only allows future analysis and use in river restoration management by experts, but also serves as information for the public. The river habitat map of Brandenburg is part of the river habitat map of the entire Germany.     

Factors affecting seasonal patterns in epilimnion zooplankton community in one of the largest man-made lakes in Africa (Lake Nasser, Egypt)

The objective of the study was to determine which factors regulate zooplankton organisms along Lake Nasser. Temperature, pH, DO, conductivity, turbidity, nutrients, and zooplankton abundance were measured. Twenty-three species of zooplankton were recorded in Lake Nasser included in Copepoda, Cladocera and Rotifera. Copepoda represented the main bulk of the community. The lowest standing stock of zooplankton was noticed during spring due to the highest fish predation during this season associated with the lowest turbidity. Big difference in temperature in Lake Nasser along the year round is considered as a controlling factor related to range of tolerance of species. The oscillation of the lake water level and the different factors affect the standing stock of zooplankton in the lake. Thus, continuous monitoring of Lake Nasser biota should be undertaken to follow the changes in the ecosystem.     

Motile phytoplankton species such as Gonyostomum semen can significantly reduce CO2 emissions from boreal lakes

Boreal lakes typically have high levels of allochthonous dissolved organic matter (DOM), causing light limitation of photosynthetic CO₂ consumption while stimulating CO₂ production. They are therefore considered as important sources of atmospheric CO₂. However, boreal lakes are also experiencing a marked expansion of bloom-forming motile phytoplankton organisms that can circumvent the shading effect of DOM by performing phototaxis and that thus might have an impact on the lakes’ CO₂ balance. We tested this idea in a DOM-rich lake using the widespread raphidophyte flagellate Gonyostomum semen as model organism. Employing continuous field measurements, we found that G. semen can reduce the partial pressure of CO₂ even at low algal densities. Periods with high algal densities were associated with CO₂ undersaturation and invasion of atmospheric CO₂. The mean daily net losses of CO₂ to the atmosphere during and after a G. semen bloom were estimated at 12.9 and 70.4 mmol C m^–2 day^–1, respectively. G. semen caused steep pCO₂ gradients in space and time, which make it difficult to unveil the species’ impact without employing continuous pCO₂ vertical profiling. This suggests that the effect of G. semen on the CO₂ balance of boreal lakes might have been overlooked in the past. Taken together, our data suggest that G. semen can significantly reduce the CO₂ emissions from boreal lakes despite high concentrations of allochthonous DOM. G. semen and other motile phytoplankton species should therefore be considered when estimating CO₂ emissions from boreal lakes, especially if these organisms continue their expansion.     

Estimation of water clarity in Taihu Lake and surrounding rivers using Landsat imagery

In China, the increase in exogenous-source pollutants from rivers is one of the most important causes of lake eutrophication. The application of remote sensing technology to water quality monitoring of rivers connected to these lakes has special significance for lake management at regional scales. Many research studies have estimated water clarity using Landsat imagery. However, most of this work focused on lakes or reservoirs, for which abundant water-only pixels (i.e., pure pixels of water, PPW) were available. Few of these studies have addressed rivers, especially rivers with an average width less than 100 m. In our study, we sought to determine whether water clarity in the rivers connected to Taihu Lake could be estimated using Landsat imagery. We obtained 18 Enhanced Thematic Mapper Plus (ETM+) images from 2009 for 13 rivers ranging from an average of 37.3 to 173.6 m wide. Three field campaigns conducted in May 2009, September 2009, and January 2010 were used to obtain field measurements of Secchi disk depth (SDD). Our results suggested that the widely used model, a(TM1/TM3) + b(TM1) + c, was suitable for the estimation of SDD for Taihu Lake. The brightness of the panchromatic band of ETM+ showed significant correlations with TM1, TM3 and TM1/TM3 (p < 0.001). As a result, SDD in the lake could also be estimated using the Landsat panchromatic band. The multispectral image of ETM+ did not provide adequate PPW for estimation of water clarity in rivers. However, PPW derived from the panchromatic image captured about 93% of the variation in SDD, on average, for the every worst-case scenario in the 13 rivers. Using the PPW in rivers, a significant correlation was found between the brightness of the panchromatic image and SDD (R² = 0.64, p < 0.001). Our results demonstrate that the panchromatic image of Landsat, but not the multispectral image, can be used to estimate water clarity in rivers with an average width greater than 40 m in the Taihu basin.     

Regional application of a fish yield estimation procedure to lakes in north-east Germany

Primary production and total phosphorus, respectively, have recently been used as the main variables to estimate the fish yield potential of lakes. In order to improve the accuracy of the estimation procedure for regional applications, two major adaptations were implemented. Both the relations between total phosphorus and primary production as well as primary production and corresponding fish yield potential were adjusted to specific regional conditions in north-east Germany and production patterns in shallow lakes, respectively. Applied to 786 lakes, the adapted procedure led to estimated fish yield potentials in the range of 8 … 67 kg/ha · a with shallow lakes showing significantly higher potentials than stratified ones. A comparison of estimated yield potentials with current yield statistics revealed an improved conformity of estimates attained by using the adapted procedure.     

Changes in the patterns of inorganic nitrogen and TN/TP ratio and the associated mechanism of biological regulation in the shallow lakes of the middle and lower reaches of the Yangtze River

The changes of NH3-N, NO3-N, NO2-N and TN/TP were studied during growth and non-growth season in 33 subtropical shallow lakes in the middle and lower reaches of the Yangtze River. There were significant positive correlations among all nutrient concentrations, and the correlations were better in growth season than in non-growth season. When TP>0.1 mgL-1, NH3-N increased sharply in non-growth season with increasing TP, and NO3-N increased in growth season but decreased in non-growth season with TP. These might be attributed to lower dissolved oxygen and low temperature in non-growth season of the hypereutrophic lakes, since nitrification is more sensitive to dissolved oxygen and temperature than antinitrification. When 0.1 mgL-1>TP>0.035 mgL-1, TN and all kinds of inorganic nitrogen were lower in growth season than in non-growth season, and phytoplank-ton might be the vital regulating factor. When TP<0.035 mgL-1, inorganic nitrogen concentrations were relatively low and NH3-N, NO2-N had significant correlations with phytoplankton, indicating that NH3-N and NO2-N might be limiting factors to phytoplankton. In addition, TN/TP went down with decline in TP concentration, and TN and inorganic nitrogen concentrations were obviously lower in growth season than in non-growth season, suggesting that decreasing nitrogen (especially NH3-N and NO3-N) was an important reason for the decreasing TN/TP in growth season. The ranges of TN/TP were closely related to trophic level in both growth and non-growth seasons, and it is apparent that in the eutrophic and hypertrophic state the TN/TP ratio was obviously lower in growth season than in non-growth season. The changes of the TN/TP ratio were closely correlated with trophic levels, and both declines of TN in the water column and TP release from the sediment were important factors for the decline of the TN/TP ratio in growth season.     

淮南采煤塌陷湖泊浮游植物优势种的营养动力学

在淮南潘谢矿区选取3个营养盐结构差异较大的塌陷湖泊,于2014—2015年4个季度分别对浮游植物群落结构组成进行调查,选取3个湖泊中的优势种(属)具尾蓝隐藻(Chroomonas caudata)、链形小环藻(Cyclotella catenata)和伪鱼腥藻(Pseudanabaena sp.)作为研究对象,设置不同的氮(N)、磷(P)浓度梯度进行营养动力学培养实验,并结合Monod方程,获得3个藻种在不同营养盐限制下的营养动力学参数.N限制下具尾蓝隐藻、小环藻和伪鱼腥藻的最大生长速率(μmax)和半饱和常数(Ks)分别为:0.66 d~(-1)、1.66 mg/L;0.37 d~(-1)、1.06 mg/L;0.71 d~(-1)、2.26 mg/L;P限制下它们的μmax和Ks则分别为:0.51 d~(-1)、0.023 mg/L;0.31 d~(-1)、0.035 mg/L;0.90 d~(-1)、0.015 mg/L.综上所述,在N充足时,伪鱼腥藻能够在竞争中形成优势,同时在P限制情况下易成为优势种,从营养动力学的角度揭示了其在塌陷湖泊中占据优势的营养盐动力学机制.研究结果可以为沉陷区水域开发利用和营养盐管理提供科学依据.     

云南高原湖泊的开发与保护

介绍了云南高原湖泊的形成演化,重点论述其在云南社会、经济发展中的地位,分析了湖泊不合理开发带来的不良生态后果,并提出了一些建议。     

山西宁武亚高山湖群浮游植物群落结构特征

通过对山西宁武亚高山湖群浮游植物群落结构的调查研究,共鉴定出浮游植物291个种、变种及变型,隶属于8门,45科,108属.各采样站点间种数相差较大,以马营海种类最多,干海最少.硅藻门、绿藻门和蓝藻门明显占优势,优势科、优势属和优势种也都较为明显.优势种有蓝藻门的细小隐球藻(Aphanocapsa elachista)、铜绿微囊藻(Microcystis aeruginisa)和小席藻(Phormidium tenue),硅藻门的库津小环藻(Cyclotella kuetzingii)、肘状脆杆藻(Fragilaria ulna)、尖针杆藻(Synedra acus),绿藻门的狭形纤维藻(Ankistrodesmus angustus)和小球藻(Chlorella vulgaris).浮游植物平均密度为3.49 × 106cells/L.水面下0.5m处比水表层的细胞密度高.综合4种生物多样性指数,宁武亚高山湖群水质总体为轻污染.     

巴丹吉林沙漠湖泊水分补给机制的模拟——以苏木吉林湖区为例

巴丹吉林沙漠气候干旱,蒸发强烈,与之形成鲜明对比的是沙漠腹地湖泊群的长久不衰,目前对于湖泊水分的补给来源仍存在争议.本文以水量均衡为基础,在苏木吉林湖区开展了降水、蒸发及湖水位和地下水位的动态监测,结合已有的水文地质资料建立地下水流动三维模型,重现湖区地下水位的季节动态变化,并基于模型进行水均衡分析.结果表明:苏木吉林湖区降水入渗补给量不足以平衡湖泊蒸发量,湖泊需要深层承压水的越流补给;湖水位和地下水位均呈现正弦曲线形态,11月最低,4月达到峰值,水位变幅分别为22和18 cm;湖区地下水多年平均总补给量为11620 m3/d,其中降水和承压水越流分别约占13%和87%,降水补给量夏季高、冬季低,承压水越流补给量季节变化不明显;承压水越流补给量可能主要来源于沙漠周边山区降水,未发现明显的水量亏空需要断裂导水来弥补.研究结果为巴丹吉林沙漠地下水资源分析及合理利用提供科学依据.     

山西运城盐池湖区藻类及分布

在山西运城盐池湖区采到的藻类植物共5门(不包括硅藻门),30科,70属,222种(含变种和变型)．其中蓝藻门4 科17属35种,绿藻门19科40属93种,裸藻门5科10属83种,黄藻门1科1属2种,轮藻门1科2属9种．该湖区的水体根据含盐量的不同可分为4种类型:淡水水体(含盐量<0．05％)、混盐水体(含盐量0．05％-3％)、真盐水体(含盐量 3％-4％)和高盐水体(含盐量>4％)．由于受含盐量的影响,藻类植物在4种水体中的分布有明显差异,随含盐量增加,种类数减少．     

Potential for remediation of acidic mining lakes evaluated by hydrogeochemical modelling: Case study Grünewalder Lauch (Plessa 117, Lusatia/Germany)

About one third of several hundred mining lakes in Eastern Germany are highly acidified, and there is a need to restore them to neutral conditions because they constitute an environmental hazard for water resources and downstream environments. The aim of this study is to evaluate the efficiency of three different acid pit lake water remediation treatments: dilution with alkaline (river) water, limestone treatment and biological neutralization by organic carbon-driven alkalinity generation. The efficiency is evaluated for the acidic mining lake Grünewalder Lauch by adjusting input values into a geochemical model and making future projections. Current approaches, such as flooding with neutral surface water or extensive liming, are not suitable for many lakes because of a limited supply of alkaline water or high lime immobilizing potential of Fe- and Al-rich water in acidic lakes, respectively. Further treatment methods are, therefore, designed to combine water supply and biological measures with the management of water quality by the application of in-lake microbial processes. These processes are focused on the metabolic response of aquatic ecosystems to nutrient enrichment (enhancement of primary production and thereby organic carbon supply) and the microbial decomposition of organic matter and their effects on the gain or loss of alkalinity.The results and comparisons of different neutralization measures will be generalized by the application of hydrogeochemical models for alkalinity production showing

a)

the long term efficiency of the measures, depending on carbon turnover at the sediment/water interface,

b)

the development of bicarbonate buffering capacity as a consequence of biological measures,

c)

the importance of pyrite formation instead of FeS.

     

云南4个湖泊浮游生物碳、氮稳定同位素的季节变化及其影响因子

浮游生物是湖泊食物网的重要组成,其碳、氮稳定同位素能够反映元素地球化学循环和食物来源的波动,是了解水域生态系统结构变化的重要手段之一.本文选取云南4个不同类型湖泊,开展浮游生物碳、氮稳定同位素组成(δ13C、δ15N)的季节变化与湖泊对比研究.大型深水湖泊(抚仙湖和阳宗海)中,浮游植物δ13C值在夏、秋季(-20.34...     

Ion deficit restricts the distribution of brown trout (Salmo trutta) in very dilute mountain lakes

The current study is, according to our knowledge, the first study indicating that ion deficit is an important restrictor to the distribution of brown trout populations in very dilute mountain lakes. The brown trout populations in the study lakes may be able to survive solely due to traces of air borne sea salt spray.